Dual-core procs will certainly benefit from the headroom. What you're talking about is chicken and egg. Yes, we won't see the benefits of DDR3 until faster memory controllers are used (although we are already up to 1066mhz FSB on Intel and 2000mhz HT on AMD), but if the RAM isn't being made, what point is there in Intel and AMD making the processors for it? Somebody has to be first, and since the DDR3 standard was pretty well set a few years back, RAM will be first, with procs and mobos to follow. If everybody just sat around and waited for the others to come up with stuff first, we'd all be posting over the Usenet on 9600baud modems, with 33mhz Turbo processors and 120mb hard drives.
I'll disagree with the idea that the majority of forum users have AMD. Over at Tweaknews, we're split at a pretty even 50/50, with a few more Intel users than AMD. In fact, many of our members run both types of systems (myself included). Regardless of that, discounting Intel sales because of forum posting is kinda silly. Neither Intel nor AMD care about a few 'net forums, and in fact, AMD has always tried to an extent to market to bigger chains (anybody else remember when Gateway and Dell both used AMD procs? The machines sucked, so they went back to Intel).
AMD people laughed at me a year ago when I said AMD would have to go to DDR2 relatively soon, they all said "no way, DDR2 isn't enough of a performance boost for AMD to even look at it", yet here we are, looking at the new AM2 with DDR2 support.